Decreased levels of plasma adiponectin associated with increased risk of colorectal cancer.

Aim: To investigate the association between adiponectin levels and risk of colorectal adenoma and cancer (early and advanced).

Methods: A cross-sectional study in a cohort of hospital-based patients was conducted between January 2004 and March 2006 at Yamagata University Hospital. Male subjects, who had colorectal tumors detected by endoscopic examination, were enrolled according to inclusion and exclusion criteria. Based on the T factor of the TNM system, intraepithelial carcinoma and submucosally invasive carcinoma were defined as early cancer, and invasion into the muscularis propria or deeper was defined as advanced cancer. The plasma levels of glucose, insulin, total cholesterol, triglyceride, high sensitivity C-reactive protein, insulin like growth factor (IGF)-1, IGF binding protein-3, adiponectin, leptin, and resistin were measured. Each factor level was designated low or high, and the risk of adenoma or cancer was estimated by univariate and multivariate logistic regression analysis.

Results: We enrolled 124 male subjects (47 with adenoma, 34 with early cancer, 17 with advanced cancer, and 26 without tumors as controls). In patients with adenoma, high triglyceride and low adiponectin were associated with a significant increase in the odds ratio (OR) by univariate analysis. Only a low adiponectin level was related to increased adenoma risk, with an adjusted OR for low level (< 11 microg/mL) to high (>or=11 microg/mL) of 5.762 (95% confidence interval (CI): 1.683-19.739, P = 0.005). In the patients with early cancer, high body mass index, high triglyceride, and low adiponectin were associated with a significant increase in OR in univariate analysis. In multivariate analysis, only low adiponectin was significantly associated with early cancer, with an adjusted OR of 4.495 (95% CI: 1.090-18.528, P = 0.038). However, in patients with advanced cancer, low adiponectin was not recognized as a significant risk factor for advanced cancer.

Conclusion: A decreased level of adiponectin is strongly associated with an increased risk of colorectal adenoma and early cancer. These data call for further investigation, including a controlled prospective study.